error handling for external person invite

1. Invite clicked on but already used
2. on v2.2 ui, I dont get an option to invite by id, but on lite ui i do
3. when i go to invite and the group doesnt exist, I get three of the same error message:

https://grouperdemo.internet2.edu/grouper_v2_2/grouperUi/appHtml/grouper.html?operation=InviteExternalSubjects.inviteExternalSubject&groupName=aStem:aGroup